Electronic structure and magnetic interactions in Mn doped semiconductors

The electronic structures of several magnetic semiconductors were calculate d using first-principles based electronic structure techniques. Calculation s were performed both for periodic supercells and for disordered systems wh ich were treated within the coherent potential approximation. Our results d iffer from the conventional atomic model for the Mn impurity. We find stron g hybridization between the majority Mn d states and the majority valence b and. We find that substitutional Mn impurities add states and electrons to the majority valence band but not to the minority. We find relatively stron g carrier induced magnetic interactions between impurities. The sign of the se interactions may however, change sign as a function of the distance betw een the impurities. (C) 2001 American Institute of Physics.